I think shes either young or plain clueless to the world around her.. I dont think you over reacted to anything. I am sorry that you felt the need to go clean it all up, but I understand why you did it, Just don't do it again , your health is more important.

Have you and her sat down and discussed and put in writing who is responsible for what.. Common sense says if everyone picks up after themselves then there is very little things that need to be shared. Please don't allow someone to treat you so poorly.

Keep your needles handy for when she doesn't pick up her things you can use them to attach a blunt note to her bedroom door to remind her to clean X